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The proper way to display multiple windows in tkinter?

I am currently working on a project using Python and tkinter.
The problem is that I don't know what's the proper way to display multiple windows, or screens, I don't know how to call them. Let me explain better.
When the application starts the login screen appears. After that, if I click register, I want to go to the register screen, but I don't want it to be a separate window (I don't want to have 2 windows displayed at the same time), but rather another window with different content ?!
How should I handle properly this situation? Create a second window using Toplevel and hiding the first (can I do that?) or changing the widgets of the first?
Code I've written so far

You can do that- just call window.withdraw() on the Toplevel you need to hide after creating a new Toplevel. Changing the widgets in the first is also an option- if you like, you could always try a Notebook widget and disable manual flipping or just put each "screen" in a frame and grid_ or pack_forget them to remove them from the window.

PyQT Qtabwidget add, remove, hide, show certain tab

I am trying to build a GUI which will:
Load a file with parameters which describe certain type of problem.
Based on the parameters of the file, show only certain tab in QTabwidget (of many predefined in Qt Designer .ui)
I plan to make a QTabwidget with, say 10 tabs, but only one should be visible based on the parameters loaded. Enabling certain tab is not an option since it takes to many space and the disabled tabs are grey. I do not want to see disabled tabs.
Removing tab could be an option but the index is not related to a specific tab so I have to take care of the shift in the indices. And furthermore if user loads another file with different parameters, a good tab should be added and the current one removed.
My questions are:
How to do this effectively?
Is it better to use any other type of widget?
In Qt designer, is it possible to define many widgets one over another and then just push the good one in front. If yes, how? And how to edit and change any of them?
If using RemoveTab, how to use pointers on tabs, rather than indices?
I use PyQt4

Use a QStackedWidget, which is exactly the same as a tab-widget, but without the tab-bar (which you don't need).
This widget is available in Qt Designer. The context menu has several commands for adding/removing pages and so forth. Note that the arrow buttons in the top-right corner are just there for convenience: they won't appear in your application.
Pages can be added/removed at runtime with addWidget/removeWidget:
index = self.stack.addWidget(self.page1)
self.stack.removeWidget(self.page1)
You can access the pages using either indexes or widget references.

I see that this thread is kinda old. But I hope this will still help.
You can use the remove() method to "hide" the tab. There's no way to really hide them in pyqt4. when you remove it, it's gone from the ui. But in the back end, the tab object with all your settings still exist. I'm sure you can find a way to improvise it back. Give it a try!

How to clear window with tkinter

Suppose I have a lovely window full of tkinter widgets all set with a function. One of these many widgets is a button. When this button is pressed, I want to 'move on to the next screen'. The next screen is in another function(including all the widgets I want to appear on that screen). I have tried to simply run the next procedure from the button, but If it does run correctly, it only adds the widgets to the existing window, and you end up with both screen#1 and screen#2 jumbled together. I have a feeling I need to use destroy, but I'm not sure how to do such, as the only way I could come up with was to group all the widgets in window 1 together in a frame, and destroy it, but I cant get access to destroy the frame from within function #2, as its a variable only within function/window #1. Sorry if that's confusing, The other option is the source, but there's a ton of widgets and other windows in progress which leads me to believe that would be even more confusing.

The simplest thing is to have your function create a single frame, and then place all of the widgets in that frame. The frame can then be placed in the main window such that it fills the whole window. Then, to delete everything you simply need to delete that one frame.
Another way to "move on to the next screen" is to use this same method, but create all of the frames ahead of time. You can stack these frames on top of each other, and use lift and/or lower to determine which one is on top. The one on top will obscure the ones below.
For an example of stacking, see Switch between two frames in tkinter
As for the problem of frame2 not knowing how to destroy frame1, you simply need to pass in a reference to the existing frame when creating a new frame, or pass in a reference to a "controller" - a function that knows about all the frames. You then ask the controller to delete the current frame, and the controller will know what the current frame is.

A button calling a function that deletes all existing frames and rebuilds another sounds like a design flaw. The propensity for errors (forgetting to delete certain elements in some places of the code etc) is pretty large.
If you don't have an insane number of UI elements, I suggest creating them all at once, and hiding/showing various elements as necessary.
Take a look at this SO answer for how you might go about creating GUI elements that can be shown/hidden, and how the callback function might look.
Edit: If you really need to do it based on these functions, then I guess an alternative approach might be this:
Say 'top_frame' is the frame that includes all your widgets which you want to destroy when you run function #2. Change all of your GUI elements in function #1 so that when you create them, you explicitly pass them top_frame so that they have a link to it (self.top_frame = top_frame). This means your button will also have an attribute self.top_frame. You pass that as one of the arguments to function #2, and function #2 now can refer to top_frame and destroy it.
But definitely prone to error and probably slower due to all the creation/destruction of GUI elements. I recommend going through the code in the answer above when you have the time, it really is a much better solution.

How to reliably append text to the end of a text box using wxPython?

Edit2: Solved! I have no idea what changed or why, but now even a RichTextCtrl appends reliably. I left the old message below, despite this.
So I'm writing a GUI in python using wxPython. One of the main elements of this GUI is a textbox.
Features I need:
The ability to reliably append text to the end of the textbox.
Prevent user editing the textbox
Vertical Scroll bar
Features I'd like:
User can select text even when more lines are being appended
Text color can be changed
With that in mind I tried to do use the RichTextCtrl provided by wxPython.
However there appears no way to reliably add text to the end of the text box. The AppendText method is not reliable. If I click a location in the textbox while several lines are being appended this way it is likely one or more of the lines will be inserted where-ever I moved the cursor.
Does anyone have any suggestions on how to reliably append text to a RichTextCtrl? I might be able to clear it and replace all of its text with new text every time I want to append something, but I fear the performance hit from this would be severe. If there is a different text control that would be more appropriate for this please suggest it.
Edit: Using a regular TextCtrl appends reliably. Still no luck with a RichTextCtrl.

AppendText works for me on Windows with wxPython 2.9. If you want to prevent the user from editing, you'll need to use the wx.TE_READ_ONLY style flag. To make a vertical scroll bar appear, add the wx.TE_MULTILINE flag too.
The wxPython demo shows how to change text color. Basically you programmatically select a range and set a style / font for that selection. Getting the ability to select text while appending may not be possible. You would probably have to set up some kind of buffer for the appends and append after the user finishes selecting or keep track of what the user is selecting, append and then reselect.

How to display parsed JSON text

Let me start off by saying that I'm starting this project to get familiar with Python. The project is to parse JSON from Reddit.com every 15 minutes and then display it with Tkinter.
Parsing the JSON text wasn't too difficult, but I'm not sure how display the text. I will need to display two things -- the title of the link and the link -- in a column style view. I was also planning on having two columns side by side to take advantage of the horizontal screen width. I've tried starting out with a Listbox, but that seemed to more be used if you want a selectable list. I just want to display the text and be done with it. Is there a different and more appropriate widget I should be using? I looked into the Entry widget a bit and thought that might be getting closer, but that seemed to only be for storing a single entry.

If you are using a sufficiently modern version of python (2.7, 3....something, I forget) you can use the ttk.Treeview widget which is similar to the listbox but supports multiple columns.
A much simpler choice is to use the text widget. You can insert the text followed by a newline. To line thimgs up in columns just insert a tab, and define an appropriate tab stop.
There are plenty of other options, but those two are arguably the best.
If you haven't dicovered it yet, tkdocs.com has a wealth of information about tkinter.